JP2025166375A - Print quality control system and print quality control method - Google Patents

Abstract

[Problem] A print quality control system is disclosed that can correct the relative position of the mask and the board for each printing direction before the deviation of the solder printed on the board from the target printing position reaches a threshold value for determining solder misalignment. [Solution] The print quality control system includes an acquisition unit and a correction unit. The acquisition unit acquires the deviation of the solder printed on the board from the target printing position by a squeegee sliding over the mask through openings in the mask for each printing direction. If the deviation acquired by the acquisition unit exceeds a second threshold value set smaller than the first threshold value for determining solder misalignment, the correction unit corrects the relative position of the mask and the board for each printing direction to reduce the deviation. [Selected Figure] Figure 3

Description

This specification discloses technology related to a print quality control system and a print quality control method.

The pre-processing unit described in Patent Document 1 executes corrective action in advance when a print defect occurs when the print condition measurement results from the print inspection machine exceed a preliminary threshold that is set stricter than the inspection threshold used by the print inspection machine to determine whether the print condition is defective. The print condition measurement results also include deviations from the target printing position of the solder printed on the board. In this way, the print quality management system described in Patent Document 1 aims to reduce the number of defects determined to be print defects (misaligned solder) by the print inspection machine compared to when pre-processing is not performed.

Furthermore, the print control unit of the printing device described in Patent Document 2 receives feedback on the inspection result data and, based on the inspection result data, can change the print parameters (printing conditions) to move the board holding table movement mechanism or print head, which can change the relative position between the board and the screen mask. In this way, the printing device described in Patent Document 2 attempts to reduce solder misalignment.

International Publication No. 2022/024326 Japanese Patent Application Laid-Open No. 2023-173291

For example, the mask is attached to a gauze (such as polyester mesh) hung on a frame member, and the tension of the mask may fluctuate as the mask is used. Fluctuations in the mask tension can cause the relative position of the mask and the board to fluctuate, potentially causing the solder to shift position and reducing print quality. Furthermore, the impact of fluctuations in the mask tension may differ depending on the printing direction.

In light of these circumstances, this specification discloses a print quality control system and print quality control method that can correct the relative position of the mask and the board for each printing direction before the deviation of the solder printed on the board from the target printing position reaches a threshold value used to determine solder misalignment.

This specification discloses a print quality control system that includes an acquisition unit and a correction unit. The acquisition unit acquires, for each printing direction, the deviation of solder printed on a substrate through an opening in a mask as the squeegee slides over the mask, relative to a target printing position. If the deviation acquired by the acquisition unit exceeds a second threshold that is set smaller than the first threshold used to determine misalignment of the solder, the correction unit corrects the relative position of the mask and the substrate for each printing direction to reduce the deviation.

This specification also discloses a print quality control method that includes an acquisition step and a correction step. The acquisition step acquires, for each printing direction, the deviation of solder printed on a substrate through an opening in a mask by sliding the squeegee over the mask from a target printing position. The correction step corrects the relative position of the mask and the substrate for each printing direction to reduce the deviation when the deviation acquired by the acquisition step exceeds a second threshold that is set smaller than a first threshold used to determine the misalignment of the solder.

This specification discloses the technical idea of changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 3" in claim 4 of the claims originally attached to the application (hereinafter referred to as the original claims). This specification also discloses the technical idea of changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 4" in claim 5 of the original claims. This specification also discloses the technical idea of changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 5" in claim 6 of the original claims.

This specification also discloses the technical idea of changing "the print quality control system described in claim 1" to "the print quality control system described in any one of claims 1 to 6" in claim 7 originally claimed. This specification also discloses the technical idea of changing "the print quality control system described in claim 1" to "the print quality control system described in any one of claims 1 to 7" in claim 8 originally claimed.

This specification also discloses the technical idea of changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 9" in claim 10, which was originally claimed. Furthermore, this specification also discloses the technical idea of changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 11" in claim 12, which was originally claimed.

The above-mentioned print quality control system makes it possible to correct the relative position of the mask and the board for each printing direction before the deviation of the solder printed on the board from the target printing position reaches the threshold value used to determine solder misalignment. What has been said above about the print quality control system also applies to the print quality control method.

FIG. 2 is a diagram showing a configuration example of a substrate-related work line; FIG. 1 is a partial cross-sectional view showing an example of the configuration of a printing press. FIG. 2 is a block diagram showing an example of a control block of a print quality control system. 10 is a flowchart illustrating an example of a control procedure performed by the print quality control system. 5A to 5C are schematic diagrams showing examples of deviations in a first direction, a second direction, and a rotational direction. FIG. 10 is a schematic diagram illustrating an example of a setting screen. FIG. 10 is a schematic diagram showing another example of the setting screen. FIG. 10 is a schematic diagram showing another example of the setting screen. FIG. 10 is a schematic diagram showing another example of the setting screen.

1. Embodiment 1-1. Configuration Example of Substrate-Related Work Line WL0 In the substrate-related work line WL0, a substrate-related work machine WM0 performs a predetermined substrate-related work on a substrate 90. The substrate-related work line WL0 of the embodiment only needs to include a printer WM1 and a print inspection machine WM2, and the type and number of substrate-related work machines WM0 that make up the substrate-related work line WL0 are not limited. As shown in FIG. 1 , the substrate-related work line WL0 of the embodiment includes a plurality (five) of substrate-related work machines WM0: a printer WM1, a print inspection machine WM2, a component placement machine WM3, a reflow oven WM4, and a visual inspection machine WM5, and the substrate 90 is transported in this order by a board transport device.

The printer WM1 prints solder 80 at multiple component mounting positions on the board 90. The print inspection machine WM2 inspects the printing condition of the solder 80 printed by the printer WM1. The component mounting machine WM3 mounts multiple components onto the board 90 on which the solder 80 has been printed by the printer WM1. There may be one or more component mounting machines WM3. When multiple component mounting machines WM3 are installed, multiple components can be mounted by sharing the load across the multiple component mounting machines WM3.

The reflow furnace WM4 heats the board 90 on which multiple components have been mounted by the component mounting machine WM3, melting the solder 80 and performing soldering. The visual inspection machine WM5 inspects the mounting state of the multiple components mounted by the component mounting machine WM3. In this way, the board-related work line WL0 uses multiple (five) board-related work machines WM0 to transport the boards 90 in sequence and perform production processes including inspection processes to produce the product board 900. The board-related work line WL0 can also be equipped with board-related work machines WM0 such as a functional inspection machine, buffer device, board supply device, board inversion device, shield mounting device, adhesive application device, and ultraviolet irradiation device as needed.

The multiple (five) substrate-related performing machines WM0 and the control device WC0 that make up the substrate-related performing line WL0 are connected to each other so that they can communicate via a communication unit LC0. The communication unit LC0 may communicate via a wired or wireless connection. Various communication methods are possible. In this embodiment, the multiple (five) substrate-related performing machines WM0 and the control device WC0 form a local area network (LAN). This allows the multiple (five) substrate-related performing machines WM0 to communicate with each other via the communication unit LC0. The multiple (five) substrate-related performing machines WM0 can also communicate with the control device WC0 via the communication unit LC0.

The management device WC0 controls the multiple (five) substrate-related operation machines WM0 that make up the substrate-related operation line WL0 and monitors the operating status of the substrate-related operation line WL0. The management device WC0 stores various control data for controlling the multiple (five) substrate-related operation machines WM0. The management device WC0 transmits control data to each of the multiple (five) substrate-related operation machines WM0. In addition, each of the multiple (five) substrate-related operation machines WM0 transmits its operating status and production status to the management device WC0.

The management device WC0 can be provided with a data server DS0. The data server DS0 can store, for example, acquired data acquired by the substrate-related performing machine WM0 regarding substrate-related performing work. For example, various image data captured by the substrate-related performing machine WM0 is included in the acquired data. Records of operating status (log data) acquired by the substrate-related performing machine WM0 are also included in the acquired data.

In addition to the image data and operating status records (log data) described above, data server DS0 can also store various production information related to the production of product boards 900. For example, component data such as information about the shape of each component type, information about electrical characteristics, and information about how components are handled is included in the production information. Inspection results from inspection machines such as print inspection machine WM2 and appearance inspection machine WM5 are also included in the production information.

1-2. Configuration Example of Printer WM1 In the printer WM1 of this embodiment, the squeegee 34 slides over the mask 70 to print solder 80 onto the substrate 90 through the openings 71 in the mask 70. As shown in FIG. 2 , the printer WM1 includes a substrate transport device 10, a mask support device 20, a squeegee moving device 30, a control device 40, and a display device 41. In this specification, the transport direction of the substrate 90 (the direction perpendicular to the paper surface of FIG. 2 ) is defined as the X direction. Furthermore, the front-to-rear direction of the printer WM1 (the left-to-right direction in FIG. 2 ), which is perpendicular to the X direction in a horizontal plane, is defined as the Y direction. The Y direction corresponds to the printing direction. Furthermore, the vertical direction (the up-down direction in FIG. 2 ), which is perpendicular to the X and Y directions, is defined as the Z direction.

The board transport device 10 transports the board 90 to be printed. The board 90 is a circuit board on which various circuits such as electronic circuits, electrical circuits, and magnetic circuits are formed. The board transport device 10 is mounted on the base BS0 of the printing machine WM1. The board transport device 10 transports the board 90, for example, by a belt conveyor extending in the transport direction (X direction) of the board 90.

The substrate transport device 10 is equipped with a substrate holding unit 11 that holds the substrate 90 that has been transported into the printing machine WM1. The substrate holding unit 11 is provided below the mask 70 and is configured to be able to move up and down in the vertical direction (Z direction) by, for example, a linear motion mechanism such as a feed screw mechanism. Specifically, the substrate holding unit 11 is lowered when the substrate 90 is transported, and when the substrate 90 is transported to a predetermined position, it rises together with the substrate 90 and holds the substrate 90 with the upper surface of the substrate 90 in close contact with the lower surface of the mask 70.

The mask support device 20 is provided above the substrate transport device 10. The mask support device 20 supports the mask 70 using a pair of support tables. The pair of support tables are located on the left side (the far side of the paper in Figure 2, as shown) and the right side (the near side of the paper in Figure 2, not shown) of the printing machine WM1 when viewed from the front, and are formed to extend along the printing direction (Y direction).

Note that Figure 2 is a partial cross-sectional view of the printer WM1 cut along the printing direction (Y direction), and shows the interior of the printer WM1 as viewed from the side, as well as cross sections of the mask 70 and substrate 90. The mask 70 has openings 71 formed therethrough at predetermined positions on the wiring pattern of the substrate 90. The mask 70 is supported by the mask support device 20, for example, via a frame member provided on the outer periphery.

The squeegee moving device 30 raises and lowers the squeegee 34 in the vertical direction (Z direction) perpendicular to the mask 70, and moves the squeegee 34 in the printing direction (Y direction) on the top surface of the mask 70. The squeegee moving device 30 includes a head driving device 31, a squeegee head 32, a pair of lifting devices 33, 33, and a pair of squeegees 34, 34. The head driving device 31 is located on the upper side of the printing machine WM1. The head driving device 31 can move the squeegee head 32 in the printing direction (Y direction) using, for example, a linear motion mechanism such as a feed screw mechanism.

The squeegee head 32 is clamped and fixed to a moving body that constitutes the linear motion mechanism of the head drive device 31. The squeegee head 32 holds a pair of lifting devices 33, 33. Each of the pair of lifting devices 33, 33 holds a squeegee 34 and can be driven independently of each other. Each of the pair of lifting devices 33, 33 drives an actuator such as an air cylinder to raise and lower the squeegee 34 it holds.

The squeegee 34 slides over the upper surface of the mask 70, moving the solder 80 supplied to the upper surface of the mask 70 along the mask 70. The solder 80 can be cream solder (solder paste). The solder 80 is imprinted onto the substrate 90 through the openings 71 in the mask 70, and the solder 80 is printed onto the substrate 90 placed on the underside of the mask 70. In this embodiment, each of the pair of squeegees 34, 34 is a plate-shaped member formed to extend along the transport direction (X direction) of the substrate 90, which is perpendicular to the printing direction (Y direction).

The front squeegee 34 of the pair of squeegees 34, 34 (left side of the paper in Figure 2) is used in a printing process that moves the solder 80 from the front side to the rear side (right side of the paper in Figure 2), with the direction from the front side to the rear side of the printer WM1 being the forward direction. The rear squeegee 34 of the pair of squeegees 34, 34 is used in a printing process that moves the solder 80 from the rear side to the front side, with the direction from the rear side to the front side of the printer WM1 being the forward direction. In addition, for both squeegees 34, the direction opposite to the forward direction is the retreating direction.

Each of the pair of squeegees 34, 34 is held by the lifting device 33 at an inclination such that the front portion located on the forward direction side faces downward. In other words, each of the pair of squeegees 34, 34 is held by the lifting device 33 at an inclination such that the back portion located on the backward direction side faces upward. The inclination angle of each of the pair of squeegees 34, 34 can be adjusted, for example, by an adjustment mechanism provided at the bottom of the lifting device 33.

The control device 40 is equipped with a known arithmetic unit and memory device, and forms a control circuit. The control device 40 is communicatively connected to the management device WC0 via the communication unit LC0 shown in Figure 1, and is capable of sending and receiving various data. The control device 40 can drive and control the substrate transport device 10, mask support device 20, squeegee movement device 30, and display device 41 based on the production program, detection results from various sensors, etc.

The control device 40 is provided with a storage device. The storage device can be, for example, a magnetic storage device such as a hard disk drive, or a storage device using semiconductor elements such as flash memory. The storage device stores production programs that drive the printing machine WM1. The control device 40 acquires various information stored in the storage device and the detection results of various sensors provided on the printing machine WM1.

The control device 40, for example, drives and controls the squeegee moving device 30. The control device 40 sends control signals to the squeegee moving device 30 based on the various information and detection results described above. This controls the positions (height) of the pair of squeegees 34, 34 held by the squeegee head 32 in the printing direction (Y direction) and vertical direction (Z direction), as well as the movement speed and tilt angle. Then, as described above, the pair of squeegees 34, 34 are driven and controlled, and solder 80 is printed on the substrate 90 placed on the underside of the mask 70.

As shown in FIG. 2, the control device 40 is provided with a display device 41. The display device 41 can display the working status of the printing press WM1. The display device 41 is also configured as a touch panel and also functions as an input device that accepts various operations by the worker. The worker can learn the working status of the printing press WM1 via the display device 41. The worker can also set up the printing press WM1 and give instructions to the printing press WM1 via the display device 41.

1-3. Example of the Configuration of the Print Quality Control System 50 There is a demand for correcting the relative positions of the mask 70 and the board 90 before the deviation PD0 of the solder 80 printed on the board 90 from the target printing position PG0 reaches the threshold value for determining misalignment of the solder 80, thereby reducing the number of defects determined to be due to poor printing conditions (misalignment of the solder 80) by the print inspection machine WM2.

Furthermore, for example, the mask 70 is attached to a gauze (such as a polyester mesh) hung on a frame member, and the tension of the mask 70 may fluctuate as the mask 70 is used. If the tension of the mask 70 fluctuates, the relative positions of the mask 70 and the substrate 90 may fluctuate, causing the solder 80 to shift position and reducing print quality. The impact of fluctuations in the tension of the mask 70 may differ depending on the printing direction.

Therefore, the substrate-to-substrate work line WL0 in this embodiment is provided with a print quality control system 50. The print quality control system 50 can correct the relative position of the mask 70 and the substrate 90 for each printing direction (Y direction) before the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 reaches the threshold value used to determine the misalignment of the solder 80. When considered as a control block, the print quality control system 50 includes an acquisition unit 51 and a correction unit 52. The print quality control system 50 can also include a pre-processing unit 53. The print quality control system 50 can also include a setting unit 54.

As shown in FIG. 3, the print quality control system 50 of this embodiment includes an acquisition unit 51, a correction unit 52, a pre-processing unit 53, and a setting unit 54. The acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 can be provided in various control devices and management devices, such as the substrate-related operation machine WM0 and management device WC0. The acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 can also be formed on the cloud.

Furthermore, the acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 can be distributed across various control devices, management devices, cloud computing, etc. For example, the acquisition unit 51 can be located in the print inspection machine WM2, the correction unit 52 and pre-processing unit 53 can be located in the printing machine WM1, and the setting unit 54 can be located in both the printing machine WM1 and the print inspection machine WM2. As shown in FIG. 3, in this embodiment, the acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 are provided in the management device WC0.

The print quality control system 50 also executes control in accordance with the flowchart shown in FIG. 4. The acquisition unit 51 performs the processes and judgments shown in steps S11 to S14. The correction unit 52 performs the processes and judgments shown in steps S15 and S16. The pre-processing unit 53 performs the processes and judgments shown in steps S17 to S20. Note that the setting unit 54 prompts the user of the printing machine WM1 to set a threshold value, which will be described later, before executing the control shown in FIG. 4. The matters described in this specification can be selected and applied as appropriate. The matters described in this specification can be combined as appropriate.

1-3-1. Acquisition unit 51
The acquisition unit 51 acquires the deviation PD0 from the target printing position PG0 of the solder 80 printed on the substrate 90 through the openings 71 of the mask 70 by the squeegee 34 sliding over the mask 70 for each printing direction (Y direction) (steps S11 to S14 shown in FIG. 4). The acquisition unit 51 may take various forms as long as it is able to acquire the deviation PD0 for each printing direction (Y direction).

For example, the printer WM1 described above uses a squeegee 34 that slides over a mask 70 to print solder 80 onto a substrate 90 through openings 71 in the mask 70. The print inspection machine WM2 can then inspect the deviation PD0 of the solder 80 printed on the substrate 90 by the printer WM1 from the target printing position PG0 for each pad. Therefore, the acquisition unit 51 can acquire the inspection results of the print inspection machine WM2 and obtain the above-mentioned deviation PD0 for each pad.

Figure 5 shows an example of the deviation PD0 of solder 80 printed on a substrate 90. The figure schematically shows the solder 80 when the substrate 90 is viewed vertically (Z direction). The target printing position PG0 indicates the center position of the target area 80g, such as a pad, when the solder 80 is ideally printed on the target area 80g without any misalignment of the solder 80. For example, the target area 80g in the figure is rectangular, and the center position of the rectangle corresponds to the target printing position PG0.

As previously mentioned, the tension of the mask 70 may fluctuate. As a result, the relative positions of the mask 70 and the substrate 90 may fluctuate, potentially causing the solder 80 to be misaligned. The actual printing position PR0 in the figure indicates the center position of the area of solder 80 actually printed on the substrate 90. The area of solder 80 in the figure is rectangular, and the center position of the rectangle corresponds to the actual printing position PR0.

As shown in the figure, the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 can be represented by a vector pointing from the target printing position PG0 to the actual printing position PR0 in the horizontal plane formed by the first direction (α direction) and the second direction (β direction). Furthermore, the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 can include a component in the rotational direction of one of the mask 70 and the substrate 90 relative to the other.

In other words, the deviation PD0 of the solder 80 printed on the board 90 from the target printing position PG0 may include at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction). The deviation PD0 in the first direction (α direction) refers to the component of the deviation PD0 that is along the printing direction (Y direction). The deviation PD0 in the second direction (β direction) refers to the component of the deviation PD0 that is perpendicular to the first direction (α direction) in the horizontal plane.

As already mentioned, in this embodiment, the second direction (β direction) corresponds to the transport direction (X direction) of the substrate 90. The deviation PD0 in the rotational direction (θ direction) refers to the component of the deviation PD0 in the rotational direction of one of the mask 70 and the substrate 90 relative to the other. The deviation PD0 shown in Figure 5 includes the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction).

Typically, multiple pads are formed on a single substrate 90, and solder 80 is printed on each of the multiple pads. The acquisition unit 51 acquires the deviation PD0 for each of the above components for the solder 80 printed on each of the multiple pads on the single substrate 90. The acquisition unit 51 can then, for example, calculate the average value of the deviation PD0 for each component, and use the calculated average value of the deviation PD0 as the deviation PD0 for each component on the single substrate 90.

Furthermore, the acquisition unit 51 can calculate, for example, the average value of the deviation PD0 for each component for at least one specific pad among the multiple pads, and use the calculated average value of the deviation PD0 as the deviation PD0 for each component for one substrate 90. The specific pad can be set arbitrarily. For example, the specific pad can include pads on which components that have a relatively short electrode pitch, such as integrated circuits, and that require relatively strict printing quality, are mounted.

Furthermore, when the acquisition unit 51 acquires the deviation PD0 from a single board 90, the stability of the acquired deviation PD0 is likely to decrease. Therefore, the acquisition unit 51 may acquire the deviation PD0 for a predetermined number of boards 90 for each printing direction (Y direction) and use the average of the acquired deviations PD0 as the deviation PD0 for each printing direction (Y direction) (steps S11 to S13 shown in Figure 4). In this case, the acquisition unit 51 can acquire the deviation PD0 in the same way as when acquiring the deviation PD0 from a single board 90.

The predetermined number of sheets corresponds to the sampling number KN0, which will be described later, and can be set arbitrarily. The larger the predetermined number of sheets, the greater the number of samples, making it easier for the acquired deviation PD0 to stabilize; however, the time required to acquire the deviation PD0 tends to increase. Therefore, the predetermined number of sheets can be set based on the required stability of the deviation PD0 and the allowable required time. For example, the predetermined number of sheets can be set to several sheets (e.g., three sheets). Furthermore, as will be described later, the predetermined number of sheets (sampling number KN0) can also be set by the user of the printing press WM1.

If the printing direction (Y direction) is different, the state of the mask 70 may vary. For example, as shown in Figures 2 and 5, the printing direction (Y direction) can include an outgoing direction (Y1 direction) and a returning direction (Y2 direction). The outgoing direction (Y1 direction) refers to the printing direction when the squeegee 34 slides in one direction over the mask 70. The returning direction (Y2 direction) refers to the printing direction when the squeegee 34 slides in the opposite direction to the outgoing direction (Y1 direction) over the mask 70.

As previously mentioned, for example, in the printer WM1 shown in Figure 2, when the printing direction (Y direction) is the outgoing direction (Y1 direction), the squeegee 34 on the front side (left side of the paper in Figure 2) moves the solder 80 from the front side to the rear side (right side of the paper in Figure 2) to print the solder 80 on the substrate 90. In this case, the rear side of the mask 70 is more likely to twist, and the tension on the front side is more likely to be higher than that on the rear side. Conversely, when the printing direction (Y direction) is the returning direction (Y2 direction), the squeegee 34 on the rear side (right side of the paper in Figure 2) moves the solder 80 from the rear side to the front side to print the solder 80 on the substrate 90. In this case, the front side of the mask 70 is more likely to twist, and the tension on the rear side is more likely to be higher than that on the front side.

As such, if the printing direction (Y direction) differs, the state of the mask 70 may change. Therefore, the acquisition unit 51 acquires the deviation PD0 of the solder 80 printed on the board 90 from the target printing position PG0 for each printing direction (Y direction) (steps S11 to S14 shown in Figure 4). In other words, the acquisition unit 51 acquires the above deviation PD0 when the printing direction (Y direction) is the forward direction (Y1 direction). The acquisition unit 51 also acquires the above deviation PD0 when the printing direction (Y direction) is the backward direction (Y2 direction).

The same applies when the acquisition unit 51 acquires the deviation PD0 for a predetermined number of boards 90. In other words, when the printing direction (Y direction) is the forward direction (Y1 direction), the acquisition unit 51 acquires the deviation PD0 for the predetermined number of boards 90 and sets the average of the acquired deviations PD0 as the deviation PD0 in the forward direction (Y1 direction). Furthermore, when the printing direction (Y direction) is the backward direction (Y2 direction), the acquisition unit 51 acquires the deviation PD0 for the predetermined number of boards 90 and sets the average of the acquired deviations PD0 as the deviation PD0 in the backward direction (Y2 direction).

It is possible that the mask 70 may experience partial deterioration of the gauze (such as polyester mesh) hung on the frame member, resulting in a partial decrease in tension. Therefore, in addition to the deviation PD0 in the first direction (α direction) that is along the printing direction (Y direction), the deviation PD0 may also include at least one of the deviations PD0 in the second direction (β direction) and the deviation PD0 in the rotational direction (θ direction).

1-3-2. Correction unit 52
When the deviation PD0 acquired by the acquisition unit 51 exceeds a second threshold TH2 that is set smaller than the first threshold TH1 used to determine misalignment of the solder 80, the correction unit 52 corrects the relative positions of the mask 70 and the board 90 in each printing direction (Y direction) so as to reduce the deviation PD0 (step S16 shown in FIG. 4). This allows the correction unit 52 to correct the relative positions of the mask 70 and the board 90 before the deviation PD0 reaches the threshold (first threshold TH1) used to determine misalignment of the solder 80.

The correction unit 52 can take various forms as long as it can correct the relative position of the mask 70 and the substrate 90 for each printing direction (Y direction) as described above. As previously described, for example, the deviation PD0 may include at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction). Therefore, the correction unit 52 corrects at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction).

For example, in the example shown in FIG. 5, a positive deviation PD0 occurs in the first direction (α direction). The first direction (α direction) is a direction along the printing direction (Y direction) and, for example, includes a positive forward direction (Y1 direction) and a negative backward direction (Y2 direction). Therefore, in this case, the correction unit 52 moves one of the mask 70 and the substrate 90 relative to the other in the backward direction (Y2 direction), which is the negative direction of the first direction (α direction), so as to reduce the positive deviation PD0 in the first direction (α direction).

Specifically, the substrate holding unit 11 of the printer WM1 shown in Figure 2 descends when the substrate 90 is transported, and when the substrate 90 is transported to a predetermined position, it rises together with the substrate 90 and holds the substrate 90 with the upper surface of the substrate 90 in close contact with the lower surface of the mask 70. In other words, the printer WM1 of this embodiment can move the substrate 90 relative to the fixed mask 70. Furthermore, the substrate holding unit 11 can move in the transport direction (X direction) of the substrate 90, the printing direction (Y direction), and the vertical direction (Z direction), and can also rotate.

Therefore, in the above example, the correction unit 52 moves the substrate holding unit 11 together with the substrate 90 in the return direction (Y2 direction) by the correction amount, and then raises the substrate holding unit 11 together with the substrate 90. The correction unit 52 then causes the substrate holding unit 11 to hold the substrate 90 with the upper surface of the substrate 90 in close contact with the lower surface of the mask 70. This reduces the positive deviation PD0 in the first direction (α direction). The correction unit 52 can similarly reduce the negative deviation PD0 in the first direction (α direction). The correction unit 52 can also similarly reduce the deviation PD0 in the second direction (β direction). Furthermore, the correction unit 52 can similarly reduce the deviation PD0 in the rotational direction (θ direction).

When the substrate 90 is loaded into the printing machine WM1, if the stopping position of the substrate 90 deviates from the target stopping position, the deviation PD0 described above will occur. Therefore, as shown in Figure 2, the printing machine WM1 of this embodiment is provided with an imaging device FC0. The imaging device FC0 can move in the transport direction (X direction) and printing direction (Y direction) of the substrate 90 using, for example, an XY table, and can capture images of the positioning reference portions provided on the mask 70 and the substrate 90.

Specifically, when the substrate 90 is transported while the substrate holder 11 is lowered, the imaging device FC0 moves to a positioning reference portion provided on the substrate 90 and captures an image of a predetermined area of the substrate 90 including the positioning reference portion. Similarly, the imaging device FC0 captures an image of a predetermined area including the positioning reference portion of the mask 70. The control device 40 processes the captured image to recognize the positioning reference portion of the substrate 90 and the positioning reference portion of the mask 70. The control device 40 adjusts the position of at least one of the mask 70 and the substrate 90 to correct for any misalignment between them. This corrects the deviation between the target stopping position and the actual stopping position of the substrate 90.

Furthermore, if an attempt is made to eliminate the deviation PD0 acquired by the acquisition unit 51 all at once, the amount of correction is likely to become large. The larger the correction amount, the more likely it is that overshoot will occur, in which the amount of movement of one of the mask 70 and the substrate 90 relative to the other becomes larger than necessary, which could result in unstable control. Therefore, it is preferable for the correction unit 52 to gradually correct the relative positions of the mask 70 and the substrate 90 with a correction amount smaller than the deviation PD0 acquired by the acquisition unit 51.

For example, the correction unit 52 can use the multiplied value obtained by multiplying the deviation PD0 acquired by the acquisition unit 51 by a predetermined reflection rate RP0 as the correction amount. The reflection rate RP0 can be set to any rate less than 100%. As described below, the reflection rate RP0 can also be set by the user of the printing machine WM1. By setting the reflection rate RP0 to a value less than 100%, the multiplied value (correction amount) becomes smaller than the deviation PD0 acquired by the acquisition unit 51. By repeating the processes and judgments shown in steps S11 to S16 in FIG. 4, the correction unit 52 can gradually correct the relative positions of the mask 70 and the substrate 90 by a correction amount smaller than the deviation PD0 acquired by the acquisition unit 51.

Furthermore, the first threshold value TH1 used to determine misalignment of the solder 80 and the second threshold value TH2, which is set smaller than the first threshold value TH1, can be set arbitrarily. As described below, for example, at least one of the first threshold value TH1 and the second threshold value TH2 can be set by the user of the printer WM1. Furthermore, the printer WM1 has a minimum correction amount MC0 that can correct the relative position of the mask 70 and the board 90, and it is difficult for the correction unit 52 to correct the relative position of the mask 70 and the board 90 with a correction amount smaller than the minimum correction amount MC0.

Therefore, the correction unit 52 may correct the relative position of the mask 70 and the substrate 90 when the deviation PD0 acquired by the acquisition unit 51 is greater than the minimum correction amount MC0 by which the relative position of the mask 70 and the substrate 90 can be corrected. In other words, the correction unit 52 does not correct the relative position of the mask 70 and the substrate 90 when the deviation PD0 acquired by the acquisition unit 51 is smaller than the minimum correction amount MC0 by which the relative position of the mask 70 and the substrate 90 can be corrected. In this way, the correction unit 52 can use the minimum correction amount MC0 as the second threshold value TH2.

As previously described, the correction unit 52 can correct at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction). Therefore, the minimum correction amount MC0 can include at least one of the minimum correction amount MC1 in the first direction (α direction), the minimum correction amount MC2 in the second direction (β direction), and the minimum correction amount MC3 in the rotational direction (θ direction). As described below, the minimum correction amount MC0 can also be set by the user of the printing press WM1. Furthermore, the correction unit 52 can use any threshold value between the minimum correction amount MC0 and the first threshold value TH1 as the second threshold value TH2.

Furthermore, if the area SH0 of the solder 80 is extremely small or extremely large, it may be erroneously recognized that the solder 80 is misaligned, even though there is no misalignment of the solder 80. For example, consider a case in which the solder 80 is printed in half of the area on the right side of the target area 80g shown in Figure 5. In this case, the solder 80 is printed within the target area 80g, and there is no misalignment of the solder 80.

However, the center position of the right half of the target area 80g shown in Figure 5 has moved to the right of the target print position PG0. As a result, the actual print position PR0 has moved to the right of the target print position PG0, which may result in the solder 80 being erroneously recognized as being misaligned, even though there is no misalignment of the solder 80. What has been described above regarding the case where the area SH0 of the solder 80 is extremely small also applies to the case where the area SH0 of the solder 80 is extremely large.

Therefore, the acquisition unit 51 may acquire the area SH0 of the solder 80 printed on the board 90. Then, the correction unit 52 may correct the relative position of the mask 70 and the board 90 if the area SH0 of the solder 80 acquired by the acquisition unit 51 falls within the allowable range SR0 set based on the target area SG0 (steps S15 and S16 shown in Figure 4). The print inspection machine WM2 can inspect the area SH0 of the solder 80 printed on the board 90 by the printer WM1 for each pad. Therefore, the acquisition unit 51 can acquire the inspection results of the print inspection machine WM2 and acquire the area SH0 of the solder 80 for each pad.

Furthermore, the target area SG0 corresponds to the area of the target region 80g shown in Figure 5. Furthermore, the allowable range SR0 need only be within a range that does not cause the above-mentioned erroneous recognition, and the lower limit value SR1 and upper limit value SR2 of the allowable range SR0 can be set arbitrarily. For example, the lower limit value SR1 and upper limit value SR2 can be set evenly around the target area SG0. Specifically, the lower limit value SR1 can be set to, for example, 90% of the target area SG0, and the upper limit value SR2 can be set to, for example, 110% of the target area SG0. Furthermore, as described below, for example, at least one of the lower limit value SR1 and the upper limit value SR2 can be set by the user of the printing machine WM1.

1-3-3. Pre-processing unit 53
As already described, the acquisition unit 51 can acquire the area SH0 of the solder 80 printed on the board 90. The predetermined condition is that the area SH0 of the solder 80 acquired by the acquisition unit 51 is not included in the allowable range SR0 set based on the target area SG0, and the area SH0 is smaller than the preliminary threshold TH4 set larger than the threshold TH3 used to determine whether the solder 80 is faded.

When the above-mentioned predetermined conditions are met, the pre-processing unit 53 executes in advance the corrective action that should be taken when thinning of the solder 80 occurs (steps S17 and S18 shown in FIG. 4). This allows the pre-processing unit 53 to execute in advance the corrective action that should be taken when thinning of the solder 80 occurs before the area SH0 of the solder 80 acquired by the acquisition unit 51 reaches the threshold value TH3 for determining thinning of the solder 80.

The threshold value TH3 and preliminary threshold value TH4 can be set arbitrarily, just like the first threshold value TH1 and second threshold value TH2. As described below, at least one of the threshold value TH3 and preliminary threshold value TH4 can also be set by the user of the printer WM1. The threshold value TH3 can be set to, for example, 50% of the target area SG0, and the preliminary threshold value TH4 can be set to, for example, 60% of the target area SG0. The pre-processing unit 53 can also execute various countermeasures. For example, clogging of the openings 71 in the mask 70 is expected to be a cause of the thinning of the solder 80.

For this reason, the pre-treatment unit 53 may perform wet cleaning of the mask 70 as a countermeasure. Wet cleaning refers to a wet cleaning method in which, for example, alcohol or the like is applied to the mask 70 for cleaning. The pre-treatment unit 53 may also use a combination of wet cleaning and dry cleaning (a dry cleaning method) as needed. The pre-treatment unit 53 may also use a vacuum (a suction-type cleaning method in which residue remaining in the opening 71 is sucked up and cleaned) as needed.

Furthermore, the specified condition is that the area SH0 of the solder 80 acquired by the acquisition unit 51 is not included in the allowable range SR0 set based on the target area SG0, and the area SH0 is greater than a preliminary threshold TH6 set smaller than the threshold TH5 used to determine whether the solder 80 has bled or bridged. If the specified condition is met, the pre-processing unit 53 executes in advance the corrective action to be taken when the solder 80 has bled or bridged (steps S19 and S20 shown in FIG. 4). This allows the pre-processing unit 53 to execute in advance the corrective action to be taken when the solder 80 has bled or bridged, before the area SH0 of the solder 80 acquired by the acquisition unit 51 reaches the threshold TH5 used to determine whether the solder 80 has bled or bridged.

The threshold value TH5 and the preliminary threshold value TH6 can be set arbitrarily, just like the first threshold value TH1 and the second threshold value TH2. As described below, at least one of the threshold value TH5 and the preliminary threshold value TH6 can also be set by the user of the printing machine WM1. The threshold value TH5 can be set to, for example, 150% of the target area SG0, and the preliminary threshold value TH6 can be set to, for example, 140% of the target area SG0. The pre-processing unit 53 can also execute various countermeasures.

The cause of the solder 80 bleeding or bridging is expected to be, for example, contamination of the mask 70. Therefore, as a countermeasure, the pre-processing unit 53 may perform dry cleaning of the mask 70. The pre-processing unit 53 may also use both wet cleaning and dry cleaning as needed. The pre-processing unit 53 may also use vacuum as needed.

1-3-4. Setting section 54
The setting unit 54 allows a user of the printer WM1 that prints the solder 80 on the substrate 90 to set a predetermined threshold value including at least one of the first threshold value TH1 and the second threshold value TH2. The setting unit 54 may take various forms as long as it allows a user of the printer WM1 to set a predetermined threshold value.

For example, the setting unit 54 can allow the user of the printing press WM1 to set a predetermined threshold value using the display device 41 of the printing press WM1. The setting unit 54 can also allow the user of the printing press WM1 to set a predetermined threshold value using the display device of the print inspection machine WM2. The setting unit 54 can also allow the user of the printing press WM1 to set a predetermined threshold value using the display device of the management device WC0. As already mentioned, for example, the display device 41 of the printing press WM1 is configured with a touch panel. For example, the user can display the work phase on the display device 41 by operating the operation units BP11 to BP41 surrounded by the dashed line BL1 in Figures 6 to 8.

When the user operates operation unit BP11, display device 41 displays the tasks in the production program creation stage. When the user operates operation unit BP21, display device 41 displays the tasks in the production stage. When the user operates operation unit BP31, display device 41 displays the tasks in the cleanup stage. When the user operates operation unit BP41, display device 41 displays the tasks in the error occurrence stage.

The user can also display the work status and setting screens for each work phase by operating operation units BP22 to BP24, which are surrounded by dashed line BL2. What has been described above about the display unit 41 of the printing machine WM1 also applies to other display units, such as the print inspection machine WM2.

Figure 6 shows an example of a settings screen. By operating the operation area BP51, the user can set the allowable range SR0 of the solder 80 area SH0, whether or not to correct the relative positions of the mask 70 and the board 90, and so on. Specifically, the user inputs the lower limit SR1 and upper limit SR2 of the allowable range SR0 of the solder 80 area SH0 as percentages. The user also selects whether or not to correct the relative positions of the mask 70 and the board 90.

Figure 7 shows another example of the settings screen. By operating the operation area BP51, the user can set whether or not to perform correction in the next production run, the number of boards 90 sampled KN0, the correction amount reflection rate RP0, the minimum correction amount MC0, and so on. Specifically, the user selects whether or not to perform correction in the next production run. The user also inputs the specified number of boards 90 sampled KN0 when the acquisition unit 51 acquires the deviation PD0.

Furthermore, the user inputs the correction amount reflection rate RP0, expressed as a percentage, by which the deviation PD0 acquired by the acquisition unit 51 is multiplied. Furthermore, the user inputs the minimum correction amount MC1 in the first direction (α direction), the minimum correction amount MC2 in the second direction (β direction), and the minimum correction amount MC3 in the rotational direction (θ direction) for the minimum correction amount MC0.

Figure 8 shows another example of the settings screen. By operating the operation area BP51, the user can set the preliminary threshold TH4, preliminary threshold TH6, number of pads, number of boards, and corrective action. For example, the settings at the top of Figure 8 indicate that the corrective action shown in Action 1 will be executed when the area of solder 80 printed on board 90 exceeds the percentage S1 (%) of the target area SG0 for the number of pads PD1 and the number of boards BD1 consecutively. Percentage S1 corresponds to the preliminary threshold TH6, and in this case, percentage S1 is set to be smaller than the upper limit (percentage) of the inspection threshold for the area of solder 80 printed on board 90.

The setting in the second row from the top indicates that when the area of solder 80 printed on the board 90 falls below percentage S2 (%) of the target area SG0 for a consecutive number of pads PD2 and boards BD2, the corrective action shown in Process 2 is executed. Percentage S2 corresponds to the preliminary threshold TH4, and in this case, percentage S2 is set to be greater than the lower limit (percentage) of the inspection threshold for the area of solder 80 printed on the board 90.

The settings in the third and fourth rows from the top are conditions and process settings for the volume of solder 80 printed on the board 90, and are set in the same way as the area of the solder 80 printed on the board 90. The user can input any number of pads and boards. Processes (countermeasures) that can be input in Processes 1 to 4 include, for example, the type of cleaning of the mask 70, abnormal shutdown of the printer WM1, and replenishing solder 80.

Figure 9 shows another example of a settings screen. This figure shows an example of a settings screen on the display device of the print inspection machine WM2. By operating the operation area BP51, the user can set a first threshold value TH1 for determining misalignment of the solder 80, a threshold value TH3 for determining smearing of the solder 80, and a threshold value TH5 for determining bleeding or bridging of the solder 80.

2. Print Quality Control Method What has already been described about the print quality control system 50 also applies to the print quality control method. Specifically, the print quality control method comprises an acquisition step and a correction step. The acquisition step corresponds to the control performed by the acquisition unit 51. The correction step corresponds to the control performed by the correction unit 52. The print quality control method can also comprise a pre-processing step. The pre-processing step corresponds to the control performed by the pre-processing unit 53. The print quality control method can also comprise a setting step. The setting step corresponds to the control performed by the setting unit 54.

3. Example of Effects of the Embodiment According to the print quality control system 50, the relative position of the mask 70 and the substrate 90 can be corrected for each printing direction (Y direction) before the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 reaches the threshold value used to determine the positional misalignment of the solder 80. What has been described above about the print quality control system 50 also applies to the print quality control method.

34: Squeegee, 50: Print quality control system, 51: Acquisition unit,
52: correction unit, 53: pre-processing unit, 54: setting unit, 70: mask,
71: opening, 90: substrate, PG0: target printing position, PD0: deviation,
TH1: first threshold, TH2: second threshold, MC0: minimum correction amount,
SG0: target area, SH0: area, SR0: tolerance,
TH3: threshold, TH4: preliminary threshold, TH5: threshold, TH6: preliminary threshold,
WM1: printing machine, Y direction: printing direction, Y1 direction: forward direction,
Y2 direction: return direction, α direction: first direction, β direction: second direction,
θ direction: rotation direction.

Claims (13)

an acquisition unit that acquires, for each printing direction, a deviation of the solder printed on the board through the openings in the mask by sliding the squeegee over the mask from a target printing position;
a correction unit that corrects the relative positions of the mask and the board for each printing direction so as to reduce the deviation when the deviation acquired by the acquisition unit exceeds a second threshold that is set smaller than a first threshold for determining misalignment of the solder; and
A print quality control system comprising: The print quality control system described in claim 1, wherein the acquisition unit acquires the deviation for a predetermined number of substrates for each printing direction, and sets the average of the acquired deviations as the deviation for each printing direction. A print quality control system as described in claim 1 or claim 2, wherein the printing direction comprises an outgoing direction in which the squeegee slides over the mask in one direction, and a returning direction in which the squeegee slides over the mask in the opposite direction to the outgoing direction. The print quality control system described in claim 1, wherein the correction unit corrects at least one of the deviations in a first direction that is a direction along the printing direction, the deviations in a second direction that is a direction perpendicular to the first direction in a horizontal plane, and the deviations in a rotational direction of one of the mask and the substrate relative to the other. The print quality control system described in claim 1, wherein the correction unit gradually corrects the relative position of the mask and the substrate by an amount of correction smaller than the deviation acquired by the acquisition unit. A print quality control system as described in claim 1, wherein the correction unit corrects the relative position of the mask and the substrate when the deviation acquired by the acquisition unit is greater than the minimum correction amount by which the relative position of the mask and the substrate can be corrected. the acquisition unit acquires an area of the solder printed on the board,
The printing quality control system according to claim 1 , wherein the correction unit corrects the relative position of the mask and the board when the area of the solder acquired by the acquisition unit is within an allowable range set based on a target area. the acquisition unit acquires an area of the solder printed on the board,
The print quality control system according to claim 1, further comprising a pre-processing unit that executes in advance the countermeasures to be taken when the solder fades when the area of the solder acquired by the acquisition unit is not within an acceptable range set based on a target area and the area is smaller than a preliminary threshold set larger than the threshold for determining the solder fade. The print quality control system described in claim 8, wherein the pre-processing unit performs wet cleaning of the mask as the corrective action. the acquisition unit acquires an area of the solder printed on the board,
The print quality control system according to claim 1, further comprising a pre-processing unit that executes in advance the countermeasures to be taken when the solder bleeds or the bridging occurs when the area of the solder acquired by the acquisition unit is not within an acceptable range set based on a target area and the area is larger than a preliminary threshold set smaller than the threshold for determining the solder bleeds or the bridging. The print quality control system described in claim 10, wherein the pre-processing unit performs dry cleaning of the mask as the corrective action. The print quality control system described in claim 1 further includes a setting unit that allows a user of the printing machine that prints the solder on the board to set a predetermined threshold value including at least one of the first threshold value and the second threshold value. an acquiring step of acquiring deviations of solder printed on the board from a target printing position for each printing direction by sliding a squeegee over the mask through openings in the mask;
a correction step of correcting the relative positions of the mask and the board for each printing direction so as to reduce the deviation when the deviation acquired by the acquisition step exceeds a second threshold set smaller than a first threshold used for determining misalignment of the solder;
A print quality control method comprising: